ProcessMA Resource


 

 

Control Chart Selection

The following table can guide you to select the control chart to use depending on the type of data, what you want to track and sample size.

Data Type Tracking Sample Charts
Variable Data Individuals Process level (individuals) Subgroup size = 1, data point >30 I Chart
Process variation (moving range) Subgroup size = 1, data point >30 MR Chart
Process level and variation Subgroup size = 1, data point >30 I-MR Chart
Subgroups Process level (means) 5-10 subgroups Xbar Chart
Process variation (ranges) 5-10 subgroups, small subgroups (<= 5) R Chart
Process variation (standard deviations) 5-10 subgroups, large subgroups (<= 5) S Chart
Process level and variation 5-10 subgroups, small subgroups (<= 5) XBar-R Chart
Process level and variation 5-10 subgroups, large subgroups (<= 5) XBar-S Chart
Process level and variation 5-10 subgroups, large subgroups (<= 5) I-MR-R/S Chart
Non-weighted Process level (Minor shifts) Subgroups >= 1, large samples MA Chart
Weighted Process level (Minor shifts) Subgroups >= 1, large samples EWMA Chart
Attribute Data Defectives (Defective product) Number of defectives Equal subgroup size NP Chart
Percentage of defectives Different (or same) subgroup size P Chart
Defects (Product can have more than one defect) Number of defects Equal subgroup size C Chart
Number defects per unit Different (or same) subgroup size U Chart